Unraveling the mechanisms of soil dominant and rare bacterial diversity during secondary forest succession: insights from niche overlap analysis

Uncovering the mechanisms underlying soil dominant and rare bacterial diversity patterns is crucial for maintaining terrestrial biodiversity. Knowledge of the driving mechanisms, especially insight from niche overlap, is limited despite some understanding of diversity during forest succession. Higher niche overlap may reduce bacterial diversity through competitive exclusion. In contrast, balanced competition caused by low and optimal niche overlap may promote the maintenance of bacterial diversity. To explore the changes in soil dominant and rare bacterial diversity and the driving mechanisms, we investigated the connections between the dominant/rare bacterial diversity and niche overlap in two forest successional chronosequences (a tropical forest in Jianfengling and a cold‐temperate forest in Mohe). Despite the different diversity patterns in the two forests, the same mechanism was applied in both forests. During secondary forest succession, dominant bacterial diversity in both forests decreased due to competitive exclusion from higher niche overlap. In comparison, rare bacterial diversity in both forests increased through balanced competition caused by low and optimal niche overlap. Furthermore, the reduced breadth of available and total phosphorus during forest succession may intensify spatial or resource limitations, thereby promoting greater niche overlap and ultimately driving the contrasting diversity patterns of dominant and rare bacteria. Our results highlight the importance of the environmental breadth‐driven niche overlap in understanding the maintenance of soil dominant and rare bacterial diversity during secondary forest succession, advancing our comprehension of the driving mechanisms of soil dominant and rare bacterial diversity in the context of forest succession.